In recent years, curved glass sheets are employed as glazing display panels in electronic devices such as mobile phones. Such curved glass sheets are conventionally produced by gravity bending methods. In a typical gravity bending method, a raw glass sheet is heated to a temperature which is equal to or higher than a glass transition temperature of the raw glass sheet, and then the glass sheet is conveyed to a first mold having an inner concave surface. The raw glass sheet is pressed to the inner concave surface by gravity to form the curved glass sheet.